In the field of research and development of polymer materials such as a liquid crystal, development of technology for measuring the optical characteristics (particularly the wavelength dependence of the retardation due to birefringence dispersion and the principal axis direction) of a measurement target has been demanded.
As measuring methods for the birefringence dispersion characteristics of a polymer material, technology of measuring the birefringence dispersion characteristics by means of a wavelength scan (see Patent Document 1), technology of simultaneously measuring the birefringence dispersion characteristics and the principal axis direction independent of a wavelength while rotating a wave plate and a polarizer (see Patent Document 2), technology enabling two-dimensional measurement of the birefringence dispersion characteristics in order to deal with a liquid crystal display production line (see Patent Document 3), and the like have been disclosed.    Patent Document 1: JP-A-2003-172691    Patent Document 2: JP-A-2005-241406    Patent Document 3: JP-A-2005-257508